Many people assume that 1MB corresponds exactly with 1,000,000 Bytes. This is not true. MB is the abbreviation of Megabyte and does not stand for million bytes as many people assume: a Megabyte has got exactly 1024*1024=1048576 Bytes. 1024 Bytes are exactly 1KB (kilobyte). For this reason there is often a misunderstanding because on a supposed 680 MB CR-R you can usually only save 650 MB: 650MB = 650 * 1024 * 1024 Bytes = 681.574.400 Bytes = 680 Million Bytes.